The invention relates generally to in-tank fuel filters and more specifically to an in-tank fuel filter having both compact size and relatively large surface area. The sophistication of modern vehicle fuel systems, particularly fuel injection systems, necessitates use of the cleanest possible fuel. Cleanest is currently defined as carrying contaminants such as foreign particulate matter having a size of less than about 100 microns. In order to satisfy these requirements, vehicle manufacturers have adopted two stage filtration schemes utilizing a first, relatively coarse fuel filter disposed in the fuel tank and a second finer, readily replaceable fuel filter in the engine compartment.
Generally speaking, the in-tank fuel filter is assembled to an in-tank fuel pump. The fuel pump is then installed in an opening in the fuel tank. Alternatively, the fuel pump may be combined with a fuel level sensor and the resulting module is similarly installed in the fuel tank. In addition to the fuel cleanliness requirements, disposition of the fuel filter in the vehicle fuel tank is often subject to constraints regarding the filter size inasmuch as vehicle manufacturers tend to prefer smaller openings in the fuel tank. Moreover, many desirable operational characteristics of fuel filters such as low pressure drop, high flow rate and extended service life are in direct conflict with the demand for reduced size. One approach to achieving both compact size and relatively large surface area and thus low pressure drop and long service life involves providing folds or pleats in the filtration media. U.S. Pat. No. 2,079,366 discloses a filter including a bag-like filter element having folds which provide a relatively large filtration area. Wire screening is placed between the folds to define separate flow channels. U.S. Pat. No. 4,479,874 to Rosenberg et al. discloses a plural layer filter having a filtration element which is folded into sections.
From the foregoing prior art, it is apparent that improvements in the art of compact, relatively high flow rate in-tank fuel filters are desirable.